1. Technical Field
The present disclosure relates to a dispersing apparatus for dispersing agglomerated particles in a slurry, a method for preparing a ceramic slurry containing ceramic particles that have been dispersed by the dispersing apparatus, a method for manufacturing a monolithic ceramic electronic component using ceramic green sheets formed of the ceramic slurry, and a monolithic ceramic electronic component manufactured by the method.
2. Background Art
In a known method for dispersal and emulsification, for preparing a ceramic slurry, a ceramic liquid containing an organic solvent or water and ceramic powder having a mean particle size in the range of 0.01 to 3 μm is dispersed under a high pressure of 10 kg/cm2 or more, and then a predetermined amount of resin or plasticizer is added to complete the ceramic slurry (see Patent Document 1).
This method produces a ceramic slurry used in the manufacture of ceramic electronic components. In the method, a ceramic slurry containing an organic solvent or water and ceramic powder having a mean particle size of 0.01 μm to 3 μm is fed to a pressuring section 52 from a feed port 51 as shown in FIG. 6. The slurry is dispersed in a mixing/dispersing section 53 under a high pressure of 10 kg/cm2 or more. The ceramic slurry dispersed under a high pressure is taken out of the discharge port 54 and a predetermined amount of resin or plasticizer is added to complete the process.
The mixing/dispersing section 53 used in the method mainly uses an impact force as a dispersing stress. However, the impact force as a dispersing stress has a broad distribution and occurs dispersedly in a wide range; hence, a high dispersing stress is difficult to produce. There are techniques to make the impact force more efficient in dispersing (including crushing and grinding) agglomerated particles, in order to achieve uniform dispersion with a desired particle size using such an impact force as the dispersing stress. For these purposes, it is advantageous to apply a high energy (pressure) to the liquid to be treated, or to circulate the liquid through the dispersing section many times. These techniques entail a long treating time. In addition, the method of Patent Document 1 produces a somewhat substantial particle size. It is thus desirable to disperse the particles into fine particles to a greater degree.
Another method for dispersal and emulsification, for example, for producing an emulsion, for example by forming fine particles (performing emulsification or dispersal), is known from Patent Document 2. In this method, a high-speed liquid jet is ejected into a cylindrical absorption cell through an end of the absorption cell while a low-speed liquid flow is produced inside the absorption cell along the axis of the liquid jet. The reduction of particle size (emulsification or dispersion) is performed by producing a high shearing stress at the interface between the high-speed liquid jet and the low-speed liquid flow.
The dispersing mechanism of this method mainly uses a shearing stress as a dispersing stress. However, the energy of the shearing stress is used for rotating the agglomerated particles, and consequently it is inefficient in dispersing (including crushing and grinding) the agglomerated particles even though it is more efficient than the dispersing stress in the foregoing Patent Document 1 (in which impact force is used as the main dispersing stress). In order to achieve more uniform dispersion with a more desired particle size using such a shearing stress as the dispersing stress, high energy (pressure) may be applied to the liquid to be treated or the liquid may be circulated through the dispersing portion many times. Thus a long treating time is entailed by this method as well. In addition, the method of Patent Document 2 produces a substantial particle size, as well. It is thus desirable to disperse the particles into fine particles to a greater degree.
Although cavitation may also be applied for dispersal, this technique does not substantially improve upon the dispersing method using impact force or shearing stress.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 11-99514
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2000-33249